Method for treating vascular occlusion

ABSTRACT

A method is disclosed for removing a vascular occlusion, such as a clot, from a blood vessel. A tubular sheath is inserted into the vessel and a self-expanding Nitinol mesh filter is deployed from a distal end of the tubular sheath at a location proximal to a clot. An inner catheter is advanced through the tubular sheath and through the mesh filter for contacting the clot. An expandable agitation element is provided along a distal end portion of the inner catheter for cutting or chopping the clot, thereby facilitating removal of the clot and improving blood flow through the vessel. Resulting clot particles are captured by the mesh filter. Negative pressure may be applied along a proximal end portion of the sheath for aspirating remaining particles. Certain embodiments of the method are well-suited for treating deep vein thrombosis and do not require the use of thrombolytic drugs.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent application No.17,065,041, filed Oct. 7, 2020, which is a continuation of U.S.application Ser. No. 16/030,622, filed Jul. 9, 2018, now U.S. Pat. No.10,799,331, which is a continuation of U.S. application Ser. No.15/834,869, filed Dec. 7, 2017, now U.S. Pat. No. 10,016,266, which is acontinuation of U.S. application Ser. No. 14/623,425, filed Feb. 16,2015, now U.S. Pat. No. 9,848,975, which is a continuation of U.S.application Ser. No. 13/597,118, filed Aug. 28, 2012, now U.S. Pat. No.8,956,386, which is a continuation of U.S. application Ser. No.12/749,233, filed Mar. 29, 2010, now U.S. Pat. No. 8,252,020, which is acontinuation of U.S. application Ser. No. 10/594,198, filed Sep. 25,2006, now U.S. Pat. No. 7,686,825, which is a National Phase Applicationof International Application No. PCT/US2005/010160, filed Mar. 25, 2005,which claims the benefit of U.S. Provisional Application No. 60/556,152,filed Mar. 25, 2004. The contents of each of the above-referencedapplications is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to medical devices and, moreparticularly, the invention relates to a filter device that is adaptedto capture and remove particles from a body lumen.

Description of the Related Art

Vascular filters are used in a wide variety of applications wherein itis desirable to capture particles from the blood. One primary use ofvascular filters is for protecting against a condition called pulmonaryembolism (PE). A pulmonary embolism occurs when a blood clot (embolus)or other particle in the cardio-pulmonary blood circulation creates apulmonary arterial blockage. A pulmonary embolism can be alife-threatening condition because the clot may effectively cut off thebody's oxygen supply. To reduce the likelihood of this event, a vascularfilter may be implanted within a blood vessel, such as the inferior venacava or other large vein, for capturing blood clots before they canreach the pulmonary vasculature. The use of vascular filters has beenparticularly useful for treating patients suffering from deep veinthrombosis (DVT), a condition wherein a blood clot (thrombus) can formin a leg and then break free (now an embolus) and migrate into thecardio-pulmonary vasculature.

Delivery of a vascular filter to a blood vessel is usually achievedthrough a peripheral vein access site, such as, for example, the jugularor femoral veins. One of the earliest examples of a vascular filter isthe Mobin-Uddin (“MU”) umbrella filter, which was developed in 1967. TheMU filter provided an alternative to a variety of treatment techniques,such as surgical ligation, caval plication, and caval clips, which wereused at the time for treating venous stasis and preventing PE. The MUfilter is composed of six flat Elgiloy spokes radiating from a hub andpartially covered by a web designed to capture blood clots. MU filterswere typically introduced into the body via a cutdown of the jugular orfemoral vein and subsequent passing of a catheter through the accesssite to the filter implant site in the infrarenal inferior vena cava.

In 1973, Greenfield et al. introduced a new stainless steel filter. Thistype of filter is conical in shape and is composed of six equally spacedstainless steel wires. The filter is adapted to hold a clot in theinfrarenal vena cava until the body's own lytic system dissolves theclot. Since the introduction of the original Greenfield filter,subsequent derivatives have been developed to reduce the size of theintroducer catheter for facilitating percutaneous introduction. Forexample, in 1989, the Titanium Greenfield Filter (TGF) was introduced asa low-profile system to facilitate the ease of percutaneous insertion.

Still other vena cava filters were introduced in the United States inthe late 1980s, including the Vena Tech-LGM vena cava filter, the Bird'sNest vena cava filter, and the Simon-Nitinol vena cava filter. The VenaTech-LGM filter is a conical filter made from a Phynox alloy, withlongitudinal stabilizing legs in addition to the intraluminal cone. TheBird's Nest filter is a “nest” of stainless steel wire which is woundinto the vena cava, while the Simon Nitinol filter is a two-stage filtermade from nickel-titanium (NiTi) alloy with a conical lower section anda petal-shaped upper section. The TrapEase filter is yet another filterthat was approved by the FDA in the summer of 2000. The TrapEase filteris laser cut from a single tube of Nitinol material and is formed with asymmetric double-basket configuration providing two levels of clottrapping.

Although vascular filters are widely used for capturing emboli in bloodvessels, existing filter configurations suffer from a variety ofshortcomings that limit their effectiveness. In one primary shortcoming,vascular filters are susceptible to clogging with embolic material. Whena filter becomes partially or totally clogged, the flow of blood throughthe vessel may be substantially reduced or stopped completely. When thisoccurs, serious complications can arise and therefore the patient mustbe treated immediately to restore adequate blood flow. Because of thepotential for clogging, existing vascular filters are typicallymanufactured with relatively large pores or gaps such that only largeemboli, such as those with diameters of 7 mm or greater, are captured.The large pore size is necessary for reducing the likelihood of cloggingdue to smaller particles. Unfortunately, in certain cases, the passageof smaller emboli may still be capable of causing a pulmonary embolismor stroke. Accordingly, physicians and filter manufacturers are requiredto balance the risk of clogging against the risk of pulmonary embolismand/or stroke.

Catheter-based mechanical thrombectomy devices provide an alternativetreatment method for removing blood clots from a patient's vasculature.Thrombectomy devices are typically used for removing a thrombus that hasformed in a blood vessel and has occluded the flow of blood. Existingthrombectomy devices include the Oasis™ Thrombectomy System by BostonScientific, the Hydrolyser™ by Cordis, the Helix™ Clot Buster® byev3/Microvena, the Arrow Trerotola PTD™ kit by Arrow International, theMTI-Cragg Brush™ by MicroTherapeutics, the Angiojet Xpeedior™ 100Catheter by Possis, and the Thrombex PMT™ system by EdwardsLifesciences.

Thrombectomy devices have gained popularity in recent years asexperience with the devices has increased. However, the use of thesedevices can be cumbersome, time-consuming and expensive. Furthermore,these devices do not capture emboli in the blood. Rather, these devicesare used to remove a thrombus that has formed within a vessel. Incertain cases, these devices may actually produce emboli and cause astroke or PE. Still further, the contact surfaces or fluid pressures ofthese mechanical thrombectomy devices may produce a variety ofundesirable side-effects, such as endothelial denudation and hemolysis.Finally, these devices have not yet proven to be sufficientlymechanically reliable for widespread use.

Therefore, due to the numerous shortcomings associated with existingvascular filters and thrombectomy devices, an urgent need exists forimproved devices and methods for capturing and removing blood clots froma patient's vasculature. The present invention addresses this need.

SUMMARY OF THE INVENTION

The present invention provides a vascular filter device adapted forcapturing and breaking down embolic material from the blood.

Preferred embodiments of the present invention generally comprise afilter body sized for deployment in a blood vessel, and an agitationmember movably coupled to the filter body. During use, movement of theagitation member acts to break apart particles captured within thefilter body. To reduce the possibility of filter migration, the filterbody may be provided with anchoring elements for engagement with aninner wall of the blood vessel. The anchoring elements may comprisepenetrating tips, barbs, hooks or any other structure configured toengage the inner wall. In another variation, the filter device may besupported by a stent structure that expands for engagement with theinner wall.

The filter body preferably comprises a plurality of elongate legscoupled together at one end to form a substantially conically-shapedbody having an interior volume configured for capturing emboli. Thevascular filter is preferably configured to be collapsible for deliveryto a treatment site. In one variation, the vascular filter isself-expanding. In another variation, the vascular filter is balloonexpandable. The filter body is coated with an anti-coagulent material.

In one aspect, the agitation member is rotatably coupled to the filterbody. A flow-receiving member may be provided for causing the agitationmember to rotate relative to the filter body. In one variation, theagitation member is capable of reversing direction during use. Ifdesired, the vascular filter may further comprise a clutch mechanismsuch that the agitation member only rotates relative to the filter bodywhen a particle is trapped within the filter body. To further enhancethe dissolution of particles trapped within the filter body, the filterbody may further comprise inwardly protruding members that cooperatewith the agitation member to break down the particle.

In another variation, movement of the agitation mechanism may beprovided by an elongate drive mechanism. The elongate drive mechanismmay be removably attachable to the agitation member or the componentsmay be provided as a single unit. The drive mechanism preferablyincludes a rotatable inner catheter contained within an outer catheter.The outer catheter couples to the filter body and remains rotationallyfixed. The inner catheter couples to the agitation member and causes theagitation member to rotate.

In another aspect, the agitation member is configured to vibrate withinthe filter body. In one preferred embodiment, the agitation membervibrates at ultrasonic frequencies.

In another aspect, the agitation member is configured to emit apressurized flow of fluid for producing hydrodynamic forces for breakingapart a clot.

In another aspect, the vascular filter further comprises an energystorage device coupled to the agitation member for producing movement ofthe agitation member.

Preferred embodiments of the present invention also provide a method ofmaking a vascular filter. In one embodiment, the method comprisesproviding a filter body sized for capturing particles from the blood andcoupling an agitation member to the filter body, wherein the agitationmember is rotatable relative to the filter body.

Preferred embodiments of the present invention also provide a method offiltering particles from blood in a blood vessel, comprising providing avascular filter having a filter body and an agitation member movablycoupled to the filter body. The method further comprises collapsing thevascular filter, inserting the vascular filter into a lumen of adelivery catheter, introducing the delivery catheter into the bloodvessel, and deploying the vascular filter from a distal end of thedelivery catheter at a desired location within the blood vessel. Afterdelivery, captured particles are broken apart by causing the agitationmember to move relative to the filter body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one method of deploying a filter device in a bloodvessel for capturing emboli.

FIG. 1A illustrates the filter device of FIG. 1 after capturing a largeembolus.

FIG. 2 is a side view illustrating an improved vascular filter accordingto one preferred embodiment of the present invention.

FIG. 3 is an enlarge view illustrating the cooperation between the shaftportion and the hub of the vascular filter of FIG. 2 .

FIGS. 4 through 6 illustrate the vascular filter of FIG. 2 during use.

FIGS. 7 and 8 illustrate alternative embodiments of a force receivingmechanism for causing the agitation member to rotate for acting on anembolus.

FIGS. 9 and 9A illustrate another alternative embodiment of a vascularfilter device wherein a spring couples the agitation member to thefilter body to allow limited longitudinal movement between the two.

FIG. 10 illustrates another alternative embodiment of a vascular filterdevice wherein a flow-receiving member comprises vanes extendingparallel to the filter body.

FIG. 11 illustrates another alternative embodiment of a vascular filterdevice wherein the agitation member is capable of reversing direction.

FIG. 12 illustrates another alternative embodiment of a vascular filterdevice further comprising an elongate drive mechanism, the drivemechanism being removably attachable to the filter device.

FIG. 12A illustrates the vascular filter device of FIG. 12 with theelongate drive mechanism coupled to the filter body for driving theagitation member.

FIG. 13 illustrates another alternative embodiment of a vascular filterdevice wherein the elongate drive mechanism, filter body and agitationmember are integrated into a single unit.

FIG. 14 illustrates the embodiment of FIG. 13 wherein the elongate drivemechanism is disposed within a lumen of a delivery sheath.

FIG. 15 illustrates the embodiment of FIG. 14 during use.

FIGS. 16 and 16A illustrate an alternative filter body embodiment havingstiffened members for creating an enclosed volume when withdrawn into adelivery sheath.

FIGS. 17A through 17C illustrate an alternative agitation member havinga controllable diameter.

FIG. 18 illustrates the embodiment of FIGS. 17A-17C during use.

FIG. 19 illustrates another alternative embodiment of a vascular filterdevice wherein the agitation member is a nozzle for emitting pressurizedfluid.

FIG. 20 illustrates another alternative embodiment of a vascular filterdevice wherein the agitation member is a vibrational mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention provide improved devicesand methods for capturing and dissolving blood clots within a patient'svasculature. In one important embodiment, the present invention providesan implantable mechanical device that is powered by the flow of bloodthrough a blood vessel. Embodiment of the present invention may be usedto capture and dissolve a wide variety of particles. As a result,embodiments of the present invention may be used to improve circulationand reduce the chance of clot-related health problems, such as strokeand pulmonary embolism.

Referring to FIG. 1 , for background purposes, a filter device 10 forfiltering particles from the blood is illustrated. The filter device isshown during implantation in the inferior vena cava 12. The filterdevice 10 is delivered to a treatment site through a catheter 14. Thedelivery catheter 14 is inserted through an access site 16 adjacent thejugular vein. With reference now to FIG. 1A, the filter device 10 isshown with a large blood clot 20 captured therein. The filter device isconfigured to hold the captured clot until the body's natural lyticsystem causes the clot to dissolve. However, as can be seen in FIG. 1A,in one primary shortcoming of the illustrated filter device, thecaptured blood clot may partially or completely occlude the flow ofblood through the inferior vena cava. Occlusion of the inferior venacava can have serious consequences and therefore requires immediatemedical attention.

With reference now to FIG. 2 , a preferred embodiment of an improvedfilter device 100 is illustrated. The filter device 100 generallycomprises a filter body 102 and an agitation member 104 movably coupledto the filter body. The agitation member 104 is coupled to a shaftportion 106 and a flow receiving member 108. In the illustratedembodiment, the shaft portion 110 extends through an opening in a hub112 for rotatably coupling the agitation member to the filter body. Asshown in the enlarge view of FIG. 3 , regions of expanded diameter 130,132 are provided along the shaft portion 110 at locations proximal anddistal to the hub 112 for preventing the agitation member 104 frommoving longitudinally with respect to the filter body 102.

The filter body 102 preferably comprises a plurality of elongate legs120 having first and second ends. The elongate legs 120 are joined alongthe first ends at the hub. In a preferred embodiment, six elongate legsare provided. In the deployed condition (as shown), the elongate legsare configured to provide the filter body 102 with a substantiallyconical shape. The filter body 102 defines an interior volume 116 whichprovides an entrapment region for capturing and holding particles. Thespacing between the elongate legs 120 can be configured for theparticular application. However, in one preferred embodiment, the legsare spaced for capturing clots having a diameter of 7 mm or greater,while allowing smaller particles to pass therethrough. The elongate legs120 are preferably arranged to create very little resistance to bloodflow through the vessel. In one variation, one or more protrudingelements 124 are provided along the inner surfaces of the elongate legs.The filter body 102 is preferably configured to be collapsible into asmaller cross-sectional profile for facilitating percutaneous deliveryto a treatment site. Although the filter body is illustrated ascomprising a plurality of elongated legs, the filter body may also takevarious alternative forms capable of capturing particles, such as, forexample, a mesh or bird's nest arrangement.

One or more anchors 122 are preferably provided along the second ends ofthe elongate legs 120 for engaging the inner wall of the blood vessel.In various preferred embodiments, the anchors may comprise barbs, hooksor any other shape well-suited for engaging the inner wall. Preferably,the anchors are sized and configured such that they do not penetratethrough the wall of the blood vessel. Over time, the anchors along theelongate legs are incorporated by endothelial tissue, therebysubstantially reducing the possibility of undesirable filter migration.In another variation, the filter device may be supported by anexpandable stent structure (not shown) that expands for engagement withthe inner wall of the vessel. The stent may be used to help improvealignment and reduce the likelihood of undesirable filter migration.

The agitation member 104 is an elongate member having corkscrew-shapedportion. The agitation member 104 is preferably disposed within theinterior volume 116 of the filter body 102. The agitation memberpreferably includes a pointed tip 126 adapted for engaging andpenetrating a captured embolus. The agitation member is formed to breakapart an embolus by producing forces which help separate the embolusinto smaller pieces which can be more easily broken down by the body'snatural lytic system. In other words, the agitation member provides amechanical element for emulsifying an embolus trapped within the filterbody. The agitation member preferably has a relatively smallcross-sectional profile such that rotational resistance will beminimized during engagement with an embolus. Although the agitationmember is illustrated as comprising a corkscrew-shaped member coupled toshaft portion and a flow receiving member, as will be described in moredetail below, any movable element configured for movement within afilter body for acting on a captured particle is contemplated to fallwithin the scope of the present invention.

The flow receiving member 108 is coupled to the shaft portion andcomprises a series of angled blades 126. The blades are configured to beacted upon by the flow of blood (shown by arrow A) for causing rotationof the shaft portion and the agitation member. The shape and arrangementof the blades is configured for producing sufficient torque to overcomeresistance caused by engagement of the agitation member with theembolus.

With reference now to FIGS. 4 through 6 , the filter device 102 is shownduring use. When an embolus 200 (or other particle in the blood) reachesthe filter device 100, the embolus 200 enters the mouth of the filterbody 102 and is funneled toward the center of the interior volume 116.The flow of blood pushes the embolus 200 into contact with the pointedtip of the agitation member 104, thereby causing the pointed tip topenetrate the captured embolus. Rotational movement causes the agitationmember to penetrate deeper into the embolus and thereby draw the embolusfurther toward the apex (i.e., cephalad end) of the filter body.

With particular reference to FIG. 5 , the filter device 100 is shownduring use as it pulls the embolus 200 into the filter body 102. As theembolus is pulled inward, it is acted on by the protruding members 124which help break apart the embolus. As the embolus is drawn further intothe filter, pieces 202 of the embolus break away. The protruding membersalso prevent the embolus from rotating with the filter body, therebyensuring that the embolus is drawn further into the filter body. Whenthe embolus 200 reaches the apex of the filter body, as shown in FIG. 6, rotational movement of the agitation member continues to impartmechanical forces on the embolus, thereby causing it to compress andeventually dissolve into harmless smaller particles. As the embolus isbroken into smaller pieces, the body's own lytic capabilities are ableto quickly dissolve the remaining pieces. The remaining particles may beheld within the filter body or the filter body may be configured with apore size sufficient to allow the harmless smaller particles to passthrough the filter wherein they may be dissolved downstream. It isrecognized that the agitation member may not penetrate all emboli thatenter the filter body. However, even if a particle enters the regionbetween the corkscrew shaped member and the filter body, the movement ofthe agitation member will still act on the particle and cause it tobreak apart over time.

To further enhance dissolution of emboli, the vascular filter may beused in combination with one or more thrombolytic drugs. In one method,the drugs may be delivered from a catheter. The fluid pressure from thedelivery of the drugs may be used to further drive the movement of theagitation member, such as by imparting forces on the flow receivingmember.

Components of the filter device are preferably manufactured frombiocompatible, non-corrosive materials having high fatigue strengths. Invarious configurations, the components of the filter device may be madeof stainless steel or titanium. In another variation, some or all of thecomponents may be made of a nickel-titanium alloy (such as Nitinol) haveshape-memory properties. In one embodiment, the nickel-titanium alloymay further include Niobium for desirable material characteristics.

Components of the vascular filter device may also be coated with one ormore drugs (e.g., therapeutic agents) to prevent cell growth onto oradjacent to the device. This feature helps reduce the likelihood ofcell/tissue ingrowth adversely affecting the functionality of the movingparts. The therapeutic agent(s) is preferably selected from the groupconsisting of antiproliferative agents, anti-inflammatory, anti-matrixmetalloproteinase, and lipid lowering, anti-thrombotic, and/orantiplatelet agent. In a variation, the elements of the device maycontain and deliver the therapeutic agent and/or the agent may beapplied to the device along certain or all surface(s) and delivered bymeans of a polymer or no polymer. In another alternative embodiment, thevascular filter device may include a radioactive element, such as aradioactive core, to reduce or prevent cell growth in the along thedevice.

Preferred embodiments of the filter device are configured to becollapsible for delivery to a treatment site. During delivery to atreatment site, the filter device is collapsed to fit within a lumen ofa delivery catheter. Preferably, the filter device is self-expandingsuch that it expands to engage the inner surface of the vessel afterdelivery. The use of shape-memory materials advantageously allows thefilter device components to be collapsed or crimped into a smalldiameter for facilitating percutaneous delivery to a treatment site,such as through a catheter or sheath. A pushing element or otherdeployment member may be used to expel the filter device from the sheathat the treatment site, wherein the filter expands to its desired shape.

With reference now to FIG. 7 , a filter device 300 is shown having analternative flow receiving member 308 configured for causing theagitation member 304 to move. In this embodiment, the flow receivingmember includes an annular element 326 located around the filter body302. It will be understood that, when an embolus is captured and heldwithin the filter body 302, blood flows through an annular gap aroundthe embolus. In other words, the blood is effectively channeled aroundthe thrombus and toward the blades. Accordingly, in this embodiment, theflow rate of blood passing along the flow receiving member isadvantageously increased when an embolus is trapped within the interiorvolume 316 of the filter body 302. As a result, the rotation of theagitation member and the available torque also increase while theembolus is captured. After the embolus has been broken down, the flowrate through the annular region decreases due to the removal of theocclusion and the resulting increased cross-sectional flow area.

In addition to the flow receiving members illustrated and describedherein, a wide variety of alternative configuration may also be used. Inany case, it is desirable that the flow receiving member be configuredto minimize hemolytic effects and the impedance of blood flow throughthe vessel. Preferably, the flow of blood should remain substantiallylaminar as it passes through the filter device. In alternativeconfigurations, it is contemplated that the flow receiving member may belocated upstream or downstream of the filter body. Alternatively, theflow receiving member may be located within the filter body itself.Still further, the flow receiving member may also function as anagitation member. With reference to FIG. 8 , an alternativeflow-receiving member 358 is provided as a threaded structure similar toan “Archimedes screw.”

With reference now to FIG. 9 , an alternative embodiment of a filterdevice 400 is illustrated wherein the agitation member 404 takes theform of a longitudinally moving body that is disposed within theinterior volume of the filter body 402. In this embodiment, theagitation member is configured to penetrate and hold a captured embolus.At least one end of the agitation member is coupled to the filter body402 by a deformable member, such as a spring 405. In this embodiment,the captured embolus is subjected to shear forces as changes in the flowrate of the blood cause the agitation to member to oscillate or pulselongitudinally within the filter body. FIG. 9A illustrates the filterdevice during use.

With reference now to FIG. 10 , another alternative embodiment of afilter device 500 comprises an agitation member 504 including aplurality of vanes 510 that are substantially parallel with the wall ofthe filter body 502. In this embodiment, the flow receiving member andthe agitation member are provided by the same structure. As theagitation member 504 rotates relative to the filter body 502, forces areexerted on a captured embolus for accelerating the dissolution of theembolus. A coupling member 520 is provided for maintaining the agitationmember 504 in the proper alignment.

With reference now to FIG. 11 , another alternative embodiment of afilter device 600 comprises an agitation member 604 that is capable ofreversing direction. First and second vanes 610, 612 extend laterallyacross the opening to the filter body 602. Projections 622 are providedat the ends of the vanes, which are received by openings 620 along therim of the filter body 602. The openings are configured such thatprojections 622 may rotate (i.e., readjust) within the openings. Whenthe projections settle in a first position, the vanes 610, 612 arepositioned to cause the agitation member to rotate in a first direction.When the projections 622 are turned 90 degrees and settle again, thevanes are then positioned to cause the rotating element to rotate in asecond direction. After being implanted in a vessel, the vane positionsmay be readjusted by the patient's movements. Alternatively, thefluctuations in the blood flow may cause the vanes to readjust. In anyevent, the reversibility of the vanes advantageously reduces thepossibility of clogging or jamming of the rotating element within thefilter body.

In yet another alternative embodiment of a filter device, a mechanicalclutch mechanism is provided such that the agitation member only rotateswhen a large clot is captured and contained within the filter. Moreparticularly, when a clot is captured within the filter, hydrodynamicforces push the clot against the agitation member, thereby overcoming abiasing force and releasing the agitation member from engagement withthe filter body such that it becomes free to rotate. In contrast, whenthere is no clot in the filter, the biasing force causes the agitationmember to advance back into the rest position wherein the engagementmembers prevent the agitation member from rotating.

In other alternative embodiments, it is contemplated that the agitationmember may be driven by an external source of power, rather than by theflow of blood through the vessel. With reference now to FIG. 12 , in onepreferred embodiment, a filter device 700 is configured to be powered byan elongate drive mechanism 750 that is advanceable through thepatient's vasculature. The drive mechanism 750 is an elongate catheterbody comprising an outer catheter 752 and an inner catheter 754. Theinner catheter is configured to rotate within and relative to the outercatheter. The outer catheter is configured to remain rotationally fixedwith respect to the filter body 702 and blood vessel. The distal end ofthe inner catheter 754 is formed with a recess 756 for mating with ashaft portion 706 of the agitation member 704. The outer catheter 752 isshaped for guiding the inner catheter into alignment with the shaftportion. With reference now to FIG. 12A, the outer catheter 752 mateswith the hub 712 to hold the filter body 702 rotatably fixed whilerotation of the inner catheter causes the agitation member to rotatewithin the filter body. The proximal end of the catheter body (notshown) extends outside of the patient and is connected to an externalpower source. Powered movement of the agitation member 704 may be usedto macerate a captured embolus in a very quick and efficient manner at ahigh rotational velocity. When the maceration is complete, the catheterbody may be withdrawn proximally such that is becomes decoupled from theshaft portion of the filter device. The catheter body may then beremoved from the patient's vasculature.

Although the system is illustrated such that the elongate catheter bodycouples to the shaft portion from the downstream side (using access viathe jugular vein), it will be appreciated that the system may beconfigured such that an elongate catheter or other drive mechanism maybe advanceable from the upstream side (using access via the femoralvein) for driving the agitation mechanism. In another variation, it iscontemplated that movement of the inner catheter is produced by manualmovement of a control mechanism by a clinician. In various preferredembodiments, the control mechanism may take the form of a rotatable knobor a pull-wire. The pull wire may be used to produce relative linearmovement of an agitation member for cutting, chopping and/or breaking upembolic material into smaller harmless pieces.

Using a vascular filter in combination with a powered (e.g.,electrically, pneumatically, hydraulically, etc.) detachable mechanicaldrive mechanism provides a very efficient and effective method ofemulsifying an embolus or other particle. In one advantage, distalembolization is minimized or eliminated because the embolus is maceratedwithin the filter body. Furthermore, the agitation member is preferablydisposed entirely within the filter body. Therefore, resulting damage tothe inner wall of the vessel is minimized or eliminated. This provides asubstantial advantage over existing mechanical thrombectomy systemswherein rotating blades or high velocity fluids can produce substantialdamage to the vessel (i.e., endothelial denudation) and thereforepresents a serious shortcoming.

With reference to FIG. 13 , in yet another alternative embodiment, apreferred configuration of the filter device 800 is well-suited forplacement in a blood vessel 830 for use as a thrombectomy system. Thefilter device 800 comprises a filter body 802 and a powered rotatableagitation member 804 integrated together as a single unit. In thisvariation, the agitation member may be entirely or partially locatedwithin the interior volume 816 of the filter body 802. However, asillustrated in FIG. 13 , the agitation member 804 is preferablylongitudinally advanceable relative to the filter body 802. In thiscase, the agitation member is disposed along the distal end portion of arotatable inner catheter 854, which is slidably and rotatably containedwithin a rotationally fixed outer catheter 852. The filter body 802 isdisposed along the distal end portion of the outer catheter 852. A hub812 may be provided at the junction between the outer catheter and thefilter body. In one advantageous feature of this embodiment, theextendable agitation member may also be used as a guidewire duringdelivery of the device to a treatment site.

With reference now to FIG. 14 , a variation of a filter device 800Awhich further comprises an aspiration catheter 820 for creating a fluidflow into the mouth of the filter body 802 and also for removingresulting particles from the vessel. The aspiration catheter may be usedfor aspirating fluid and particles from the vessel before, during orafter maceration of an embolus. As illustrated, the aspiration cathetermay be combined with the drive catheter into a single device. Theaspiration catheter may further provide a delivery sheath for deliveringthe filter body to the treatment site.

With reference now to FIG. 15 , the filter device 800A of FIG. 14 isshown during use. After being advanced through a vessel 830 to atreatment site, negative pressure is applied at a proximal end of theaspiration catheter 820 to create a fluid flow into the mouth of thefilter body 802. The inner catheter 854 may then be rotated for causingthe agitation member 804 to rotate. While the agitation member isrotating, it may be advanced toward a thrombus 200 (or other particle)for macerating the thrombus and thereby removing the occlusion. Duringthe maceration of the thrombus, resulting particles are drawn into theinterior volume 816 of the filter body 802. Particles small enough topass through the filter body are drawn into the aspiration catheter. Ascan be seen, this embodiment provides a very safe and effectivemechanism for removing a thrombus from a blood vessel without any dangerof distal embolization. It can further be seen that the filter helpscenter the agitation member such that the inner wall of the vessel isnot damaged. At the end of the procedure, the inner catheter 854, outercatheter 852 and filter body 802 may all be withdrawn into theaspiration catheter 820 (or sheath) for safe removal from the patient'svasculature. It may be desirable to continue applying negative pressurealong the proximal end of the aspiration catheter during removal suchthat the particles are not released from the filter.

With reference now to FIG. 16 , an alternative filter body 852 isillustrated for further reducing the likelihood of particles escapingfrom the filter device. In this embodiment, the filter body 852 isformed with a plurality of stiffened members 854 which are hingedlyattached to the hub 812. A flexible membrane 860 is disposed over thestiffened members. The stiffened members are biased into the openposition to form a hemispherically-shaped filter body when in thenon-constrained condition. With reference now to FIG. 16A, when thefilter body 852 is withdrawn into an aspiration catheter 820 (orsheath), the stiffened members hingedly rotate (or flex) adjacent to thehub. Due to the curved shape of the stiffened members, when in theconstrained condition, the distal ends of the stiffened member cometogether such that the distal opening of the filter body is nearly orcompletely closed, thereby preventing any particles from escaping. Themembrane is configured to fold as the stiffened members come together.

With reference now to FIGS. 17A through 17C, an alternative agitationmember 904 is illustrated wherein the diameter of the distal end iscontrollable. In this embodiment, the agitation member 904 may bedisposed at the distal end of a rotatable inner catheter 906, similar tothe device described above with reference to FIG. 15 . However, in thisembodiment, the agitation member comprises two flexible members 910, 912disposed along the distal end of the inner catheter 906. In theillustrated embodiment, the flexible members further comprise weightedtips 920, 922. As the inner catheter 906 rotates, centrifugal forcescause the flexible members 910, 912 to flex outward away from the axisof rotation, thereby effectively increasing the diameter of theagitation member 904. Therefore, it can be seen that the diameter of theagitation member can be controlled by varying the rotational velocity ω(omega) of the inner catheter. For example, at ω₁ the diameter of theagitation member is D₁, as shown in FIG. 17A. At ω₂ the diameter of theagitation member is D₂, as shown in FIG. 17B. Finally, at ω₃ thediameter of the agitation member is D₃, as shown in FIG. 17C.

With reference now to FIG. 18 , it can be seen that this featureadvantageously allows the clinician to control the diameter of theagitation member to suit the diameter of the vessel 940 being treated.This allows for efficient thrombectomy without damaging the inner wallof the vessel. More particularly, the inner catheter 906 is advanceddistally through an outer catheter 930 and out from the interior volumeof the filter body 902. The inner catheter is rotated at a rotationalvelocity that causes its diameter to match the particular application.The rotating agitation member 904 may then be advanced for removingdebris, such as an embolus 200, from the vessel 940. If desired,particles may be aspirated through the aspiration catheter 920.

With reference now to FIG. 19 , in yet another alternative embodiment ofthe filter device, an agitation member 944 comprises a nozzle or jet 946for emitting a pressurized fluid flow. In the illustrated embodiment,this feature is used in combination with the inner catheter, outercatheter, filter body and aspiration catheter arrangement describedabove. However, in this embodiment, it is not necessary for the innercatheter to be rotatable. Rather, the inner catheter is configured witha fluid delivery lumen. If desired, the inner catheter may be configuredto be deflectable, such as by using a pull wire of the type known in theart. The fluid delivered to the thrombus may be saline or any suitablefluid. In one variation, the fluid may comprise at least in part athrombolytic drug for helping to break down the thrombus (or otherparticle).

With reference now to FIG. 20 , in yet another alternative embodiment ofthe filter device, the agitation member 980 is configured to producevibrational energy to help dissolve particles. In one variation, theagitation member 980 is capable of producing ultrasonic vibrations. Thevibrations may be produced by movement of a mechanical mechanism, suchas a vibrating ball. In another embodiment, the vibration may beproduced by a transducer, such as a piezoelectric element 982 whichoscillates in response to an electrical input. Ultrasonic vibrationalenergy may be used to quickly and efficiently dissolve (lyse) a clot,primarily by disrupting the fibrin matrix of the clot. The disruption iscreated by mechanical energy as well as by the formation of microbubblescaused by cavitation of fluids in the clot or in the surrounding bloodor tissue. When ultrasound is used, the vibrations are provided in therange of about 19 to 45 kHz with a power input ranging from about 15 to25 Watts. If desired, the delivery of vibrational (e.g., ultrasonic)vibrations to the clot may be accompanied by the delivery ofthrombolytic drugs. The power required to produce the vibration of theagitation mechanism may be provided by electricity, such as through awire in a catheter, through hydraulic pressure, or from an energystorage device contained within the filter device.

In yet another alternative embodiment of a filter device, an electriccurrent may be delivered to the filter device for driving a motorlocated on the filter device. For example, when delivered temporarily,such as during an angioplasty procedure, an elongate wire may beprovided for delivering an electrical current to an electric motorcontained with the filter device, preferably along the hub. In variousalternative embodiments, an electrical current may be applied to theagitation member or the filter body to help dissolve embolic material orother particles through electrical dissolution, rather than bymechanical maceration.

In yet another alternative embodiment of a filter device, an energystorage device, such as a battery, may be contained within the filterdevice for providing powered movement of the rotating member. In onevariation, a control mechanism may be provided for turning the power onand off. In one example, the control mechanism may include a remotetransmitter for sending a signal, such as by a RF signal, which turns aswitch on and off. In this variation, the movable element only rotateswhen desired. In another embodiment, the filter device may furthercomprise a sensing mechanism, such as a pressure sensor of the typeknown in the art, for detecting when a clot is present in the filter.The sensing mechanism may be used to turn the agitation member on andoff when necessary.

In yet another alternative embodiment, the agitation member is made, atleast in part, of a ferro-magnetic material. In this embodiment, avariable magnetic field is used to produce movement (e.g., rotation) ofthe agitation member in the filter body by macerating particles. Asufficiently powerful magnetic field may be created outside of thepatient's body by techniques known in the art.

In one alternative method of use, embodiments of the present inventionare well-suited for use with patients undergoing total hip or kneereplacement surgery. In this subset of patients, the risk of embolism isshort-term and is typically limited to a definable period of time.Accordingly, for these patient's, it may be desirable to provide atemporary filter device coupled to a tether for facilitating removalthereof. The tether may take the form of a flexible elongate membercoupled to the filter device in a manner as known in the art. Duringuse, the tethered temporary filter device is preferably deployed from acatheter and is implanted in the infrarenal vena cava with the tetherextending out of the puncture site in the neck (jugular) or groin(femoral), or buried subcutaneously within the soft tissues in thepatient's neck. The tether remains coupled to the filter afterdeployment. When it is desirable to remove the filter, the tether may beused to manipulate the filter from a location outside the body. Forexample, the filter may be pulled proximally such that it is withdrawninto a catheter lumen. This embodiment may also be used for retrieving afilter during the initial deployment procedure. This is particularlyuseful when the initial deployment orientation is not desirable.

Although the improvements disclosed herein are primarily discussed inthe context of use with a vascular filter for use in a blood vessel, thedevice described herein may also be used in a wide variety of other bodylumens. In one alternative application, embodiments of the vascularfilter may be used in the coronary arteries. The device may be deliveredfor use during an angioplasty procedure to help break down embolicdebris released during the procedure. In one embodiment, the pulse ofblood after removal of angioplasty balloon can be used to rotate theblades. Still further, the principles of the present invention may beapplicable to any application, not necessarily biological, wherein it isdesirable to capture and break apart particles.

While the foregoing detailed description has described severalembodiments of the apparatus of the present invention, it is to beunderstood that the above description is illustrative only and is notlimiting of the disclosed invention. It will be appreciated that thespecific features of the invention can differ from those described abovewhile remaining within the scope of the present invention. For example,the present invention is intended to include any filter device having amovable component within the interior volume for breaking apart capturedparticles and thereby providing a self-cleaning device. The movablecomponent may be powered by the flow of a fluid through the filter or byan internal or external source of power.

What is claimed is:
 1. A system for removing a vascular thrombus from ablood vessel of a patient, comprising: a catheter having a lumen and adistal end portion; a self-expanding filter body including a permeablebraided mesh configured to capture and hold clot material while theself-expanding filter body is withdrawn, and the self-expanding filterbody also being configured for blood to pass therethrough and having aproximal end portion with a tapered shape and an open distal end sizedto conform to an inner wall of the blood vessel when deployed in theblood vessel, wherein the proximal end portion of the self-expandingfilter body is attached to the distal end portion of the catheter andthe distal end of the self-expanding filter body is configured to bedeployed distally with respect to the distal end portion of thecatheter; and an inner elongated member configured to extend through thelumen of the catheter and through the self-expanding filter body, theinner elongated member having a thrombus engagement member, and thethrombus engagement member having flexible radially extending membersthat diverge radially outward in a distal direction and are expandableto an expanded profile having an expanded diameter sized for contactingthe thrombus when deployed in the blood vessel, wherein the members eachhave a radially-outward most portion that is at least partially rounded,and wherein the inner elongated engagement member and the thrombusengagement member are longitudinally slidable for disrupting andremoving the thrombus from the blood vessel; wherein the self-expandingfilter body is adapted for capturing thrombus material that has beenacted upon by the thrombus engagement member.
 2. The system of claim 1wherein the inner elongated member is moveable linearly with respect tothe catheter such that thrombus engagement member moves linearly as itengages the thrombus.
 3. The system of claim 1, further comprising anouter catheter having a lumen, and wherein the catheter is configured tobe received in the outer catheter.
 4. The system of claim 1 wherein thepermeable braided mesh comprises a permeable nitinol mesh.
 5. A methodof capturing and removing a thrombus from a blood vessel in a human,comprising: advancing an inner elongated member having a thrombusengagement member to a thrombus in the blood vessel; positioning acatheter in the blood vessel such that a distal end of the catheter isproximal to the thrombus in the blood vessel; deploying a filter bodyhaving a braided mesh with a tapered proximal end portion and an opendistal end such that the open distal end of the filter body self-expandsto a diameter of the vessel at a location between the distal end of thecatheter and the thrombus, wherein a proximal end portion of the filterbody is attached to a distal end of the catheter; expanding the thrombusengagement member and moving the thrombus engagement member linearlysuch that it engages and disrupts the thrombus, wherein the thrombusengagement member has flexible radially extending members that divergeradially outward in a distal direction and are capable of engaging thevessel wall, and wherein the members each have a radially-outward mostportion that is at least partially rounded; and capturing thrombusmaterial with the filter body and holding the captured thrombus materialin the filter body while the filter body is withdrawn from the bloodvessel.
 6. The method of claim 5 wherein expanding the thrombusengagement member comprises expanding the thrombus engagement membersuch that it is at least adjacent the blood vessel wall.
 7. The methodof claim 5 wherein expanding the thrombus engagement member comprisesexpanding the thrombus engagement member to suit the diameter of theblood vessel.